# Endpoints for API users ### Message A message represents a message sent through a campaign. As each campaign is associated with one message template and has its own API key, you will need to keep track of your API keys if you wish to send messages in different campaigns. You will not be able to send or retrieve a message in a campaign inaccessible to yourself, even if you know the relevant ID(s). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://postman-v2.guides.gov.sg/endpoints-for-api-users/endpoints-for-api-users.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.